ES2966732T3 - Crystal with electrical connection element - Google Patents

Abstract

The present invention relates to a disc comprising: - a substrate (1), - an electrically conductive structure (2) in a region of the substrate (1), - a layer of a solder mass (4) in a region of the electrically conductive structure (2), - at least one electrical connection element (3) containing a chromium steel with a chromium content greater than or equal to 10.5% by weight, - at least two welding points (15, 15') of the connection element (3) on the welding mass (4), where - the welding points (15, 15') form at least one contact surface (8) between the connection element (3) and the electrically conductive structure (2).) and - the shape of the contact surface (8) forms at least one segment of an oval, an ellipse or a circle with a central angle α of at least 90°. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Crystal with electrical connection element

The invention relates to a glass with an electrical connection element and to an economical and environmentally friendly method for its manufacture.

The invention further relates to a glass with an electrical connection element for vehicles with electrically conductive structures, such as, for example, heating conductors or antenna conductors. Electrically conductive structures are usually connected to the on-board network using welded electrical connection elements. Because the materials used have different coefficients of thermal expansion, mechanical stresses occur that strain the glass and can cause it to break during manufacturing and operation.

Lead-containing solders have a high ductility that can compensate for the mechanical stresses that occur between an electrical connection element and the glass through plastic deformation. However, due to Directive 2000/53/EC on end-of-life vehicles, in the EC lead-containing solders must be replaced with lead-free solders. The directive is, in short, the acronym ELV (End of Life Vehicles). The goal is to ban extremely problematic components in products resulting from the massive rise in disposable electronics. The substances affected are lead, mercury and cadmium. This concerns, among other things, the implementation of lead-free soldering materials in electrical applications on glass and the introduction of corresponding replacement products.

Document EP 1 942 703 A2 describes an electrical connection element in vehicle windows, where the difference in the thermal expansion coefficient of the glass and the electrical connection element is < 5 * 10-6/°C and the The connection contains predominantly titanium and the contact surface between the connection element and the electrically conductive structure is rectangular. To allow adequate mechanical stability and processability, it is proposed to use excess solder material. The excess solder material leaves the intermediate space between the connecting element and the electrically conductive structure. Excess welding material causes high mechanical stresses in the glass. These mechanical stresses eventually cause the glass to break.

US 2644066 and GB 751536 A each show a connecting element that does not contain chromium-containing steel and is soldered by a lead-containing solder to an electrically conductive layer.

The objective of the present invention is to provide a glass with an electrical connection element and an economical and environmentally friendly manufacturing method, which avoids critical mechanical stresses in the glass.

The object of the present invention is achieved according to the invention by a device according to independent claim 1. Preferred embodiments are evident from the dependent claims.

The glass according to the invention with at least one electrical connection element has the following characteristics:

- a substrate,

- an electrically conductive structure in a region of the substrate,

- a layer of a solder material over an electrically conductive region of the structure, and

- at least two welding points of the connecting element on the welding material, where

- the welding points form at least one contact surface between the connecting element and the electrically conductive structure, and

- the shape of the contact surface has at least one oval, ellipse or circle segment with a central angle of at least 90°.

The central angle of the segment is 90° to 360°, preferably 140° to 360°, for example, 180° to 330° or 200° to 330°. Preferably, the shape of the contact surface between the connecting element and the electrically conductive structure has at least two semi-ellipses, particularly preferably two semi-circles. Most preferably, the contact surface is configured as a rectangle with two semicircles arranged on opposite sides. In a particularly preferred alternative embodiment of the invention, the shape of the contact surface has two circular segments with central angles of 210° to 360°. The shape of the contact surface may also comprise, for example, two segments of an oval, an ellipse or a circle, the central angle being 180° to 350°, preferably 210° to 310°.

In an advantageous configuration of the invention, the weld points form two spaced apart contact surfaces between the connecting element and the electrically conductive structure. Each contact surface is disposed on the surface of one of the two leg regions of the connecting element facing the substrate. The leg regions are connected to each other by a bridge. The two contact surfaces are connected to each other via the bridge surface facing the substrate. The shape of each of the two contact surfaces has at least one oval, ellipse or circle segment with a central angle of 90° to 360°, preferably 140° to 360°. Each contact surface may have an oval, preferably elliptical, structure. Particularly preferably, each contact surface is in the shape of a circle. Alternatively, each contact surface is preferably configured as a circular segment with a central angle of at least 180°, particularly preferably at least 200°, very particularly preferably at least 220° and in particular at least 230°. The circular segment may have, for example, a central angle of 180° to 350°, preferably of 200° to 330°, particularly preferably of 210° to 310°. In another advantageous configuration of the connecting element according to the invention, each contact surface is configured as a rectangle with two semi-ovals, preferably semi-ellipses, particularly preferably semi-circles arranged on opposite sides.

An electrically conductive structure is applied to the glass. The electrical connection element is electrically connected to the electrically conductive structure in subregions by a solder material.

The connecting element is joined by welding, for example resistance welding, across the contact surface or contact surfaces to the electrically conductive structure. In resistance welding, two welding electrodes are used, each welding electrode being brought into contact with a welding point of the connecting element. During the welding process a current flows from one welding electrode to the second welding electrode through the connecting element. The contact between the welding electrode and the connecting element preferably occurs on as small a surface as possible. For example, welding electrodes have a pointed design. The small contact surface causes a high current density in the contact region between the welding electrode and the connecting element. The high current density causes heating of the contact region between the welding electrode and the connecting element. The heat distribution extends from each of the two contact regions between the welding electrode and the connecting element. For simplicity, isotherms can be represented in the case of two point heat sources as concentric circles around the welding points. The exact shape of the heat distribution depends on the shape of the connecting element. Heating in the region of the contact surfaces between the connecting element and the electrically conductive structure causes melting of the solder material.

According to the state of the art, the connecting element is preferably connected to the electrically conductive structure, for example, via a rectangular contact surface. Due to the distribution of heat propagating from the welding points, temperature differences occur along the edges of a rectangular contact surface during the welding process. As a result, there may be regions of the contact surface where the solder material is not completely melted. These regions lead to poor adhesion of the connecting element and mechanical stresses in the glass.

The advantage of the invention lies in the formation of the contact surface or contact surfaces between the connecting element and the electrically conductive structure. The shape of the contact surfaces is, at least in a predominant region of the edges, rounded and preferably presents circles or circular segments. The shape of the contact surfaces approximates the shape of the heat distribution around the welding points during the welding process. Consequently, only small or no temperature differences occur along the edges of the contact surfaces during the welding process. This results in a uniform fusion of the solder material throughout the region of the contact surfaces between the connecting element and the electrically conductive structure. This is especially advantageous in terms of the adhesion of the connecting element, the reduction of the duration of the welding process and the avoidance of mechanical stresses on the glass. In particular, there is a special advantage in using a lead-free solder material, which due to its lower ductility can compensate mechanical stresses less well compared to lead-containing solder materials.

The connecting elements have, in plan view, for example preferably, a length and a width of 1 mm to 50 mm, and particularly preferably a length and a width of 2 mm to 30 mm, and very particularly preferably a width and a width from 2 mm to 8 mm and a width from 10 mm to 24 mm long.

Two contact surfaces connected to each other by a bridge have, for example, preferably a length and width of 1 mm to 15 mm and, particularly preferably, a length and width of 2 mm to 8 mm.

The solder material exits with an exit width of < 1 mm from the intermediate space between the connecting element and the electrically conductive structure. In a preferred embodiment, the maximum exit width is preferably less than 0.5 mm and, in particular, approximately 0 mm. This is especially advantageous in terms of reducing mechanical stresses in the glass, adhesion of the connecting element and reducing the amount of solder.

The maximum exit width is defined as the distance between the outer edges of the connecting element and the crossing point of the solder material, where the solder material falls below a layer thickness of 50 |μm. The maximum exit width is measured on the solidified weld material after the welding process.

A desired maximum outlet width is obtained by appropriate selection of the volume of the solder material and the vertical distance between the connecting element and the electrically conductive structure, which can be determined by simple experiments. The vertical distance between the connecting element and the electrically conductive structure can be predefined by a suitable process tool, for example a tool with an integrated separator.

The maximum exit width can even be negative, that is, retreat into the intermediate space formed by an electrical connection element and an electrically conductive structure.

In an advantageous configuration of the glass according to the invention, the maximum outlet width is withdrawn into a concave meniscus in the intermediate space formed by the electrical connection element and the electrically conductive structure. A concave meniscus is created, for example, by increasing the vertical distance between the spacer and the conducting structure during the welding process, while the weld is still fluid.

The bridge between two foot regions of the connecting element according to the invention preferably has a sectionally planar shape. Particularly preferably, the bridge is composed of three planar segments. “Flat” means that the bottom of the connecting element forms a plane. The angle between the surface of the substrate and the bottom of each planar segment of the bridge directly adjacent to a foot region is preferably <90°, particularly preferably between 1° and 85°, most particularly preferably between 2° and 75°, and in particular between 3° and 60°. The bridge is shaped such that each flat segment adjacent to a foot region is inclined in the opposite direction to the immediately adjacent foot region.

The advantage lies in the action of the capillary effect between the electrically conductive structure and the bridge segments adjacent to the contact surfaces. The capillary effect is a consequence of the small distance between the electrically conductive structure and the bridge segments adjacent to the contact surfaces. The small distance results from the <90° angle between the substrate surface and the bottom of each planar section of the bridge directly adjacent to a foot region. The desired distance between the connecting element and the electrically conductive structure is adjusted according to the fusion of the solder material. The excess solder material is sucked in a controlled manner through the capillary effect towards the volume delimited by the bridge and the electrically conductive structure. This reduces the crossing of the solder material at the outer edges of the connecting element and thus the maximum exit width. Therefore, a reduction in mechanical stress in the glass is achieved.

In the context of the definition of the maximum exit width, the edges of the contact surfaces with which the bridge is connected are not outer edges of the connecting element.

The cavity delimited by the electrically conductive structure and the bridge can be completely filled with solder material. Preferably, the cavity is not completely filled with solder material.

In another advantageous configuration of the invention, the bridge is curved. The bridge can have only one direction of curvature. The bridge preferably has the profile of an oval arch, particularly preferably the profile of an elliptical arch and very particularly preferably the profile of a circular arch. The radius of curvature of the circular arc is, for example, preferably 5 mm to 15 mm, with a length of the connecting element of 24 mm. The direction of curvature of the bridge can also change.

The bridge may also be composed of at least two sub-elements that are in direct contact with each other. The projection of the bridge in the plane of the substrate surface may also be curved. The direction of curvature preferably changes in the center of the bridge. The bridge does not have to have a constant width.

In an advantageous configuration of the invention, each of the two welding points is arranged on a contact projection. The contact projections are arranged on the surface of the connecting element away from the substrate. The contact bosses preferably contain the same alloy as the connecting element. Preferably, each contact projection is convexly curved, at least in the region opposite the surface of the substrate. Each contact projection is configured, for example, as a segment of a rotating ellipsoid or as a spherical segment. Alternatively, the contact shoulder may be cube-shaped, with the surface facing away from the substrate curved convexly. The contact projections preferably have a height of 0.1 mm to 2 mm, particularly preferably 0.2 mm to 1 mm. The length and width of the contact projections are preferably between 0.1 and 5 mm, most preferably between 0.4 mm and 3 mm. The contact projections can be embossed. In an advantageous embodiment, the contact projections can be configured in one piece with the connecting element. The contact projections can be formed, for example, by transforming the surface of a connecting element with a flat surface in the initial state, for example, by stamping or deep drawing. In this case, a corresponding depression can be created on the surface of the connecting element opposite the contact projection.

For welding, electrodes whose contact side is flat can be used. The surface of the electrode is brought into contact with the contact shoulder. In this case, the surface of the electrode is arranged parallel to the surface of the substrate. The point on the convex surface of the contact shoulder that has the greatest vertical distance from the surface of the substrate is disposed between the surface of the electrode and the surface of the substrate. The contact region between the electrode surface and the contact shoulder forms the welding spot. The position of the welding spot is preferably determined by the point on the convex surface of the contact shoulder that has the greatest vertical distance from the surface of the substrate. The position of the welding point is independent of the position of the welding electrode on the connecting element. This is especially advantageous with regard to a uniform and reproducible heat distribution during the welding process. Heat distribution during the welding process is determined by the position, size, arrangement and geometry of the contact shoulder.

In an advantageous configuration of the invention, at least two spacers are arranged on each of the contact surfaces of the connecting element. The spacers preferably contain the same alloy as the connecting element. Each separator has the shape, for example, of a cube, a pyramid, a segment of a rotational ellipsoid or a segment of a sphere. The dividers preferably have a width of 0.5 * 10-4 m to 10 x 10-4 m and a height of 0.5 * 10-4 m to 5 * 10-4 m, particularly preferably 1 x 10-4 m to 3 * 10-4m. The spacers promote the formation of a uniform layer of solder material. This is especially advantageous with regard to the adhesion of the connecting element. The separators may be formed in one piece with the connecting element. The spacers can be formed, for example, at the contact surface by transforming a connecting element with flat contact surfaces in the initial state, for example, by stamping or deep drawing. In this case a corresponding depression can be created on the surface of the connecting element opposite the contact surface.

By means of the contact projections and spacers, a homogeneous, uniformly thick and uniformly melted layer of the solder material is obtained. In this way, the mechanical stresses between the connecting element and the glass can be reduced. This is particularly advantageous with the use of a lead-free solder material, which due to its lower ductility can compensate mechanical stresses less well compared to lead-containing solder materials.

The substrate preferably contains glass, particularly preferably flat glass, float glass, quartz glass, borosilicate glass, soda-lime glass. In an alternative preferred embodiment, the substrate contains polymers, particularly preferably polyethylene, polypropylene, polycarbonate, polymethyl methacrylate and/or mixtures thereof.

The substrate has a first coefficient of thermal expansion. The connecting element has a second coefficient of thermal expansion.

The first coefficient of thermal expansion is preferably 8 * 10-6/°C to 9 * 10-6/°C. The substrate preferably contains glass preferably having a thermal expansion coefficient of 8.3*10-6/°C to 9*10-6/°C in a temperature range of 0°C to 300°C.

In another advantageous embodiment of the invention, the difference between the first and second expansion coefficient is also <5*10-6/°C. The second coefficient of thermal expansion is preferably 9 * 10-6/°C to 13 * 10-6/°C, particularly preferably 10 * 10-6/°C to 11.5 * 10-6/°C in a Temperature range from 0°C to 300°C.

The connecting element according to the invention contains a chromium-containing steel with a chromium content greater than or equal to 10.5% by weight and a thermal expansion coefficient of 9 * 10-6/°C to 13 * 10-6/ °C. Other alloy components, such as molybdenum, manganese or niobium, lead to better corrosion stability or a change in mechanical properties, such as tensile strength or cold formability.

The advantage of connecting elements made of chromium-containing steel compared to titanium connecting elements according to the prior art lies in better weldability. It results from the higher thermal conductivity of 25 W/mK to 30 W/mK compared to titanium's thermal conductivity of 22 W/mK. The higher thermal conductivity results in more uniform heating of the connecting element during the welding process, thereby avoiding the occasional formation of particularly hot spots (“hot spots”). These points are starting points for further damage to the glass. In this way, better adhesion of the connecting element to the glass is achieved. Chromium-containing steel is also easy to weld. This allows a better connection of the connecting element to the on-board network by soldering through an electrically conductive material, for example copper. Thanks to the better cold formability, the connecting element can also be better crimped with the electrically conductive material. Additionally, chromium-containing steel is more available.

The electrically conductive structure according to the invention preferably has a layer thickness of 5 pm to 40 pm, particularly preferably of 5 pm to 20 pm, very particularly preferably of 8 pm to 15 pm and in particular of 10 pm to 12 pm. The electrically conductive structure according to the invention preferably contains silver, particularly preferably silver particles and glass frits.

The layer thickness of the weld according to the invention is preferably <3.0*10-4 m.

The soldering material is lead-free, that is, it is lead-free. This is especially advantageous with regard to the environmental impact of the glass with an electrical connection element according to the invention. Lead-free soldering materials usually have less ductility than lead-containing soldering materials, so that mechanical stresses between the connecting element and the glass can be less compensated. However, it has been shown that the critical mechanical stresses are clearly reduced by means of the connecting element according to the invention. The solder material according to the invention preferably contains tin and bismuth, indium, zinc, copper, silver or their compositions. The proportion of tin in the solder composition according to the invention is from 3% by weight to 99.5% by weight, preferably from 10% by weight to 95.5% by weight, particularly preferably from 15% by weight to 60%. in weigh. The proportion of bismuth, indium, zinc, copper, silver or compositions thereof in the solder composition according to the invention is from 0.5% by weight to 97% by weight, preferably from 10% by weight to 67% by weight , where the proportion of bismuth, indium, zinc, copper or silver may be 0% by weight. The soldering composition according to the invention may contain nickel, germanium, aluminum or phosphorus in a proportion of 0% by weight to 5% by weight. The soldering composition according to the invention contains, very particularly preferably, Bi40Sn57Ag3; Sn40Bi57Ag3; Bi59Sn40Ag1; Bi57Sn42Ag1; In97Ag3; Sn95.5Ag3.8Cu0.7; Bi67ln33; Bi33In50Sn17; Sn77.2In20Ag2.8; Sn95Ag4Cu1; Sn99Cu1; Sn96.5Ag3.5; or mixtures thereof.

The connecting element according to the invention is preferably coated with nickel, tin, copper and/or silver. Particularly preferably, the connecting element according to the invention is provided with an adhesion-promoting layer, preferably of nickel and/or copper, and in addition with a solderable layer, preferably of silver. Very particularly preferably, the connecting element according to the invention is coated with nickel from 0.1 pm to 0.3 pm and/or silver from 3 pm to 20 pm. The connecting element can be plated with nickel, tin, copper and/or silver. Nickel and silver improve the current carrying capacity and corrosion stability of the connecting element and wetting with the solder material.

The iron-nickel alloy, the iron-nickel-cobalt alloy or the iron-chromium alloy can also be welded, crimped or glued as a compensation plate on a connecting element made of, for example, steel, aluminum, titanium, copper. As a bimetal, a favorable expansion behavior of the connecting element can be obtained with respect to the expansion of the glass. The compensation plate is preferably hat-shaped.

The electrical connection element contains on the surface facing the solder material a coating containing copper, zinc, tin, silver, gold or alloys or layers thereof, preferably silver. This prevents the weld material from extending beyond the coating and limits the exit width.

The shape of the electrical connection element may form solder deposits in the space between the connection element and the electrically conductive structure. Solder deposits and wetting properties of the solder on the connecting element prevent the solder material from leaving the interspace. Weld deposits can be rectangular, rounded or polygonal.

The welding heat distribution and therefore the distribution of the welding material during the welding process can be defined by the shape of the connecting element. The solder material flows towards the warmest point. The connecting element may have, for example, a single or double hat shape, to advantageously distribute heat in the connecting element during the welding process.

The introduction of energy during the electrical connection of the electrical connection and the electrically conductive structure is preferably carried out by means of punches, thermodes, piston welding, preferably laser welding, hot air welding, induction welding, resistance welding and/ or by ultrasound.

The objective of the invention is further achieved by a method for the production of a crystal with at least one connecting element, wherein

a) solder material is applied on the contact surface or on the contact surfaces as a platelet with a fixed thickness, volume and layer shape,

b) an electrically conductive structure is applied to a region of a substrate,

c) the connection element with the welding material is arranged on the electrically conductive structure,

d) energy is introduced into the welding points, and

e) the connection element is welded to the electrically conductive structure.

The soldering material is preferably pre-applied to the connecting elements, preferably in the form of platelets with a fixed layer thickness, volume, shape and arrangement on the connecting element.

The connection element can be welded or crimped, for example, onto a sheet metal, a stranded wire or a mesh, for example made of copper, and connected to the on-board electrical network.

The connecting element is preferably used in heated windows or with antennas in buildings, in particular in automobiles, railways, airplanes or boats. The connection element serves to connect the conductive structures of the crystal to electrical systems arranged outside the crystal. Electrical systems are amplifiers, control units or voltage sources.

The invention is explained in more detail by means of drawings and illustrative embodiments. The drawing is a schematic representation and not full scale. The drawing does not limit the invention in any way. In the figures:

a Figure 1 shows a plan view of a first embodiment of the glass according to the invention,

a Figure 1a shows a schematic representation of the heat distribution during the welding process, a Figure 2a shows a section A-A' through the glass according to Figure 1,

a Figure 2b shows a section B-B' through the glass according to Figure 1,

a Figure 2c shows a C-C' section through the crystal according to Figure 1,

a Figure 3 shows a section C-C' through an alternative crystal according to the invention,

a Figure 4 shows a section B-B' through another alternative glass according to the invention, a Figure 5 shows a section B-B' through another alternative glass according to the invention, a Figure 6 shows a section B-B' through another alternative glass according to the invention, a Figure 7 shows a section A-A' through another alternative glass according to the invention, a Figure 8 shows a section A-A' through another alternative glass according to the invention, a Figure 8a shows a section A-A' through of another alternative glass according to the invention,

a Figure 9 shows a plan view of an alternative embodiment of the glass according to the invention,

a Figure 9a shows a section D-D' through the glass according to Figure 9,

Figure 10 shows a plan view of an alternative embodiment of the connecting element,

a Figure 11 shows a plan view of another alternative embodiment of the connection element,

a Figure 11a shows a section E-E' through the connecting element according to Figure 11,

a Figure 12 shows a plan view of another alternative embodiment of the connection element,

a Figure 13 shows a plan view of another alternative embodiment of the connection element,

a Figure 13a shows a section F-F' through the connecting element according to Figure 13,

a Figure 14 shows a detailed flow chart of the method according to the invention.

Figures 1, 2a, 2b and 2c respectively show a detail of a heatable glass 1 according to the invention in the region of the electrical connection element 3. Glass 1 is a 3 mm thick thermally prestressed single-layer safety glass, made of soda-lime glass. Glass 1 has a width of 150 cm and a height of 80 cm. An electrically conductive structure 2 in the form of a heating conductive structure 2 is printed on the glass 1. The electrically conductive structure 2 contains silver particles and glass frits. In the edge region of the glass 1, the electrically conductive structure 2 is widened to a width of 10 mm and forms a contact surface for the electrical connection element 3. In the region of the edge of the glass 1 there is also a coating silkscreen (not shown). The connecting element 3 consists of two leg regions 7 and 7' that are connected to each other via the bridge 9. Two surfaces 8' and 7' facing the substrate are arranged on the surfaces of the leg regions 7 and 7' facing the substrate. 8'' contact. In the region of the contact surfaces 8' and 8'', the soldering material 4 establishes a durable electrical and mechanical connection between the connecting element 3 and the electrically conductive structure 2. The solder material 4 contains 57% by weight of bismuth, 40% by weight of tin and 3% by weight of silver. The soldering material 4 is completely arranged between the electrical connection element 3 and the electrically conductive structure 2 by a predefined volume and shape. The welding material 4 has a thickness of 250 pm. The electrical connection element 3 is made of steel of material number 1.4509 according to EN 10 088-2 (ThysenKrupp Nirosta® 4509) with a thermal expansion coefficient of 10.0 * 10-6/°C. Each of the contact surfaces 8' and 8'' has the shape of a circular segment with a radius of 3 mm and a central angle a of 276°. The bridge 9 consists of three planar segments 10, 11 and 12. The surface of each of the two segments 10 and 12 facing the substrate forms an angle of 40° with the surface of the substrate 1. The portion 11 is arranged parallel to the substrate surface 1. The electrical connection element 3 has a length of 24 mm. The two leg regions 7 and 7' have a width of 6 mm; bridge 9 has a width of 4 mm.

A contact projection 14 is provided on each of the surfaces 13 and 13' of the leg regions 7 and 7' facing away from the substrate. The contact projections 14 are hemisphere-shaped and have a height of 2.5*10-4 m and a width of 5*10-4 m. The centers of the contact projections 14 are arranged vertically to the surface of the substrate above the circular centers of the contact surfaces 8' and 8''. The welding points 15 and 15' are arranged at the points on the convex surface of the contact projections 14 that have the greatest vertical distance from the surface of the substrate.

Three spacers 19 are arranged on each of the contact surfaces 8' and 8''. The spacers 19 are hemisphere-shaped and have a height of 2.5*10-4 m and a width of 5*10-4 m.

Steel of material number 1.4509 according to EN 10088-2 has good cold forming properties and good welding properties in all methods except gas welding. The steel is used for the construction of soundproofing systems and exhaust gas detoxification systems and is particularly suitable for this due to its resistance to scaling up to more than 950 °C and corrosion resistance to the stresses that occur in the exhaust gas system.

Figure 1a schematically shows a simplified representation of the heat distribution around the welding points 15 and 15' during the welding process. The circular lines are isotherms. The shape of the contact surfaces 8' and 8'' of the connection elements 3 of Figure 1 adapts to the heat distribution. Therefore, the solder material 4 melts uniformly and completely in the region of the contact surfaces 8' and 8''.

Figure 3 represents, following the illustrative embodiment of Figures 1 and 2c, an alternative embodiment of the connection element 3 according to the invention. The electrical connection element 3 is provided on the surface facing the solder material 4 with a silver-containing coating 5. This prevents the solder material from extending beyond the liner 5 and limits the exit width b. In another embodiment, an adhesion-promoting layer, for example, of nickel and/or copper, may be located between the connecting element 3 and the silver-containing layer 5. The exit width b of the welding material 4 is less than 1 mm. Due to the arrangement of the welding material 4, no critical mechanical stresses are observed in the crystal 1. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 is permanently stable.

Figure 4 represents, following the illustrative embodiment of Figures 1 and 2c, another alternative embodiment of the connection element 3 according to the invention. The electrical connection element 3 contains on the surface facing the solder material 4 a recess with a depth of 250 μm, which forms a solder reservoir for the solder material 4. It is possible to completely prevent the exit of the welding material 4 from the intermediate space. The thermal stresses in the glass 1 are not critical and a durable electrical and mechanical connection is provided between the connecting element 3 and the glass 1 through the electrically conductive structure 2.

Figure 5 represents, following the illustrative embodiment of Figures 1 and 2c, another alternative embodiment of the connection element 3 according to the invention. The leg regions 7 and 7' of the electrical connection element 3 are bent upwards in the marginal regions. The height of the upward curvature of the edge regions of the glass sheet 1 is at most 400 pm. This forms a space for the welding material 4. The predefined welding material 4 forms a concave meniscus between the electrical connection element 3 and the electrically conductive structure 2. It is possible to completely prevent the exit of the welding material 4 from the intermediate space. The width b of the outflow, at approximately 0, is less than zero, largely due to the meniscus formed. The thermal stresses in the glass 1 are not critical and a durable electrical and mechanical connection is provided between the connecting element 3 and the glass 1 through the electrically conductive structure 2.

Figure 6 shows another alternative embodiment of the connection element 3 according to the invention with contact surfaces 8' and 8'' in the form of circular segments and a bridge 9 of planar shape in sections. The connecting element 3 contains an iron-containing alloy with a thermal expansion coefficient of 8 * 10-6/°C. The thickness of the material is 2 mm. In the region of the contact surfaces 8' and 8'' of the connecting element 3, hat-shaped compensation elements 6 are applied with chromium-containing steel of material number 1.4509 according to EN 10088-2 (ThyssenKrupp Nirosta® 4509). The maximum layer thickness of the hat-shaped compensation members 6 is 4 mm. By means of the compensation members it is possible to adapt the thermal expansion coefficients of the connection element 3 to the needs of the glass 1 and the welding material 4. The hat-shaped compensation members 6 result in better heat flow during the manufacture of the welded connection 4. The heating occurs mainly in the center of the contact surfaces 8' and 8''. It is possible to further reduce the output width b of the welding material 4. Thanks to the reduced outlet width b < 1 mm and the adapted expansion coefficient, it is possible to further reduce the thermal stresses in glass 1. The thermal stresses in glass 1 are not critical and a durable electrical and mechanical connection is provided between the connection element 3 and the glass 1 through the electrically conductive structure 2.

Figure 7 represents, following the illustrative embodiment of Figures 1 and 2a, an alternative embodiment of the connection element 3 according to the invention. Bridge 9 is curved and has the profile of a circular arc with a radius of curvature of 12 mm. The thermal stresses in the glass 1 are not critical and a durable electrical and mechanical connection is provided between the connecting element 3 and the glass 1 through the electrically conductive structure 2.

Figure 8 represents, following the illustrative embodiment of Figures 1 and 2a, another alternative embodiment of the connection element 3 according to the invention. Bridge 9 is curved and changes its direction of curvature twice. Next to the leg regions 7 and 7', the direction of curvature is away from the substrate 1. Therefore, there are no edges at the connections 16 and 16' between the contact surfaces 8' and 8'' and the bottom of the bridge 9. The lower part of the connecting element 3 has a continuous progression. The thermal stresses in the glass 1 are not critical and a durable electrical and mechanical connection is provided between the connecting element 3 and the glass 1 through the electrically conductive structure 2.

Figure 8a represents, following the illustrative embodiment of Figures 1 and 2a, another alternative embodiment of the connection element 3 according to the invention. The bridge 9 consists of two planar segments 22 and 23. The surface of each of the two segments 22 and 23 facing the substrate forms an angle of 20° with the surface of the substrate 1. Together, the surfaces of the two segments 22 and 23 facing the substrate form an angle of 140°. The thermal stresses in the glass 1 are not critical and a durable electrical and mechanical connection is provided between the connecting element 3 and the glass 1 through the electrically conductive structure 2.

Figures 9 and 9a show in each case a detail of another embodiment of the crystal 1 according to the invention in the region of the electrical connection element 3. Connecting element 3 contains steel of material number 1.4509 according to EN 10088-2 (ThyssenKrupp Nirosta® 4509). The leg regions 7 and 7' are connected to each other via the bridge 9. The bridge 9 consists of three segments 10, 11 and 12 of planar shape. Each of the contact surfaces 8' and 8'' is shaped like a rectangle with semicircles arranged on opposite sides. The connecting element 3 has a length of 24 mm. Bridge 9 has a width of 4 mm. The contact surfaces 8' and 8'' are 4 mm long and 8 mm wide.

A contact projection 14 is provided on each of the surfaces 13 and 13' of the leg regions 7 and 7' facing away from the substrate 1. Each contact projection 14 is parallelepiped-shaped with a length of 3 mm and a width of 1 mm, the surfaces facing away from the substrate 1 being convexly curved. The height of the contact protrusions is 0.6 mm. The welding points 15 and 15' are arranged at the points on the convex surface of the contact projections 14 that have the greatest vertical distance from the surface of the substrate. Two spacers 19 having the shape of hemispheres with a radius of 2.5*10-4 m are arranged on each of the contact surfaces 8' and 8''. Due to the arrangement of the welding material 4, no critical mechanical stresses are observed in the crystal 1. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 is permanently stable.

Figure 10 represents a plan view of an alternative embodiment of the connection element 3 according to the invention. The leg regions 7 and 7' are connected to each other via the bridge 9. The contact surfaces 8 and 8' are formed as circular segments with a radius of 2.5 mm and a central angle a of 280°. Bridge 9 is curved. The width of the bridge is reduced from the connections 16 and 16' with the contact surfaces 8 and 8' towards the center of the bridge. The minimum width of the bridge is 3 mm. Due to the arrangement of the welding material 4, no critical mechanical stresses are observed in the crystal 1. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 is permanently stable.

In an alternative embodiment of the invention, the connection element 3 with the contour of Figure 10 is not configured in the form of a bridge. In this case, the connection element 3 is connected through a contact surface 8 over its entire surface with the electrically conductive structure.

Figures 11 and 11a each represent a detail of another alternative embodiment of the connection element 3 according to the invention. The two leg regions 7 and 7' are connected to each other via the bridge 9. Each contact surface 8' and 8'' is in the shape of a circular segment with a radius of 2.5 mm and a central angle a of 286°. . Bridge 9 consists of two subelements. The sub-elements respectively have a curved subregion 17 and 17' and a flat subregion 18 and 18'. Bridge 9 is connected to leg region 7 through subregion 17 and to leg region 7' through subregion 17'. The curvature directions of the subregions 17 and 17' are directed away from the substrate 1. The planar subregions 18 and 18' are arranged perpendicular to the surface of the substrate and are in direct contact with each other. The contact projections 14 are in the form of hemispheres with a radius of 5 * 10-4 m. The 19 separators are in the form of hemispheres with a radius of 2.5 * 10-4 m. The connecting element 3 has a length of 10 mm. The 7th and 7th leg regions have a width of 5 mm; bridge 9 has a width of 3 mm. The height of the bridge 9 from the surface of the substrate 1 is 3 mm. The height of the bridge 9 may preferably be between 1 mm and 5 mm. Due to the arrangement of the welding material 4, no critical mechanical stresses are observed in the crystal 1. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 is permanently stable.

Figure 12 shows a plan view of another alternative embodiment of the connection element 3 according to the invention. The two leg regions 7 and 7' are connected to each other via a curved bridge 9. Each contact surface 8' and 8'' is shaped like a circle with a radius of 2.5 mm. The two connections 16 and 16' between the leg regions 7 and 7' and the bridge 9 are arranged completely on different sides of the direct connection line between the circular centers of the contact surfaces 8' and 8''. The projection of the bridge in the plane of the substrate surface is curved. In this case, the direction of curvature changes at the center of the bridge. Laterally, in the center of the bridge 9, two convexities opposite each other are arranged in the form of circular segments with radii of 2 mm. The radii of the convexities may preferably be between 1 mm and 3 mm. The convexities can, for example, also have a rectangular shape with a preferred length and width of 1 mm to 6 mm. In the region of the bridge 9 delimited by the edges of the convexities, an electrically conductive material can be applied, for example, by welding or crimping, for connection to the on-board electrical system. Due to the arrangement of the welding material 4, no critical mechanical stresses are observed in the crystal 1. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 is permanently stable.

Figures 13 and 13a represent in each case a detail of another alternative embodiment of the connection element 3 according to the invention. The connection element 3 is connected over its entire surface to the electrically conductive structure 2 through a contact surface 8. The contact surface 8 is shaped like a rectangle with semicircles arranged on opposite sides. The contact surface has a length of 14 mm and a width of 5 mm. The connecting element 3 is curved upward throughout the edge region 20. The height of the edge region 20 from the glass 1 is 2.5 mm. The height of the edge region 20 may, in alternative embodiments of the invention, preferably be between 1 mm and 3 mm. An extension element 21 is arranged on the folded edge of one of the two straight sides of the connecting element 3. The extension element 21 consists of a curved subregion and a flat subregion. The extension member 21 is connected to the marginal region 20 of the connecting member 3 through the curved subregion and the curvature direction is towards the opposite side of the connecting member 3. The extension element 21 has a length of 11 mm and a width of 6 mm in plan view. The extension member 21 may preferably have a length of between 5 mm and 20 mm, particularly preferably between 7 mm and 15 mm, and a width of 2 mm to 10 mm, particularly preferably 4 mm to 8 mm. For example, an electrically conductive material can be applied to the extension element 21 for connection to the on-board electrical system, for example by welding, crimping or in the form of a plug-in connector. Due to the arrangement of the welding material 4, no critical mechanical stresses are observed in the crystal 1. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 is permanently stable.

Figure 14 represents in detail a method according to the invention for the production of a crystal 1 with an electrical connection element 3. An example of the procedure according to the invention for the manufacture of a glass with an electrical connection element 3 is presented there. As a first stage, it is necessary to divide the welding material 4 according to its shape and volume. The welding material 4 in portions is arranged on the contact surface 8 or the contact surfaces 8' and 8'' of the electrical connection element 3. The electrical connection element 3 is arranged with the welding material 4 on the electrically conductive structure 2. By means of the input of energy at the welding points 15 and 15', a lasting connection of the electrical connection element 3 with the electrically conductive structure 2 and, therefore, with the glass 1 is made.

Example

Test specimens were manufactured with glass 1 (thickness 3 mm, width 150 cm and height 80 cm), electrically conductive structure 2 in the form of a heating conductive structure, electrical connection element 3 according to Figure 1, silver layer 5 on the contact surfaces 8' and 8'' of the connection element 3, and the welding material 4.

The material thickness of the connecting element 3 was 0.8 mm. The connecting element 3 contained steel of material number 1.4509 according to EN 10088-2 (ThyssenKrupp Nirosta® 4509). Three spacers 19 were arranged on each of the contact surfaces 8' and 8''. Each welding point 15 and 15' was arranged on a contact projection 14. The soldering material 4 was previously applied in the form of a platelet with a fixed layer thickness, volume and shape on the contact surfaces 8' and 8'' of the connecting element 3. The connecting element 3 was applied with the welding material 4 applied to the electrically conductive structure 2. The connecting element 3 was welded to the electrically conductive structure 2 at a temperature of 200 °C and a processing time of 2 seconds. The outflow of the welding material 4 from the intermediate space between the electrical connection element 3 and the electrically conductive structure 2, which exceeded a layer thickness t of 50 |μm, was observed only up to a maximum outlet width of b = 0.4mm. The dimensions and compositions of the electrical connection element 3, the silver layer 5 on the contact surfaces 8' and 8'' of the connection element 3 and the soldering material 4 are found in Table 1. In glass 1 there is no Critical mechanical stresses were observed due to the arrangement of the welding material 4, predefined by the connecting element 3 and the electrically conductive structure 2. The connection of the crystal 1 with the electrical connection element 3 via the electrically conductive structure 2 was permanently stable.

In all samples it could be observed, with a temperature difference of 80 °C to -30 °C, that no glass substrate 1 was broken or damaged. It could be shown that shortly after welding these crystals 1 with the welded connecting element 3 were stable against a sudden drop in temperature.

In addition, test specimens were made with a second composition of the electrical connection element 3. In this case, connecting element 3 contained an alloy of iron, nickel and cobalt. The dimensions and compositions of the electrical connection element 3, the silver layer 5 on the contact surfaces 8' and 8'' of the connection element 3 and the soldering material 4 are found in Table 2. With a material output 4 welding from the intermediate space between the electrical connection element 3 and the electrically conductive structure 2, which exceeded a layer thickness t of 50 μm, an average exit width of b = 0.4 mm was obtained. Also in this case it could be observed that with a temperature difference of 80 °C to -30 °C no glass substrate 1 broke or showed damage. It could be shown that shortly after welding these crystals 1 with the welded connecting element 3 were stable against a sudden drop in temperature.

In addition, test specimens were made with a third composition of electrical connection element 3. In this case, connecting member 3 contained an iron-nickel alloy. The dimensions and compositions of the electrical connection element 3, the silver layer 5 on the contact surfaces 8' and 8'' of the connection element 3 and the soldering material 4 are found in Table 3. With a material outlet 4 welding from the intermediate space between the electrical connection element 3 and the electrically conductive structure 2, which exceeded a layer thickness t of 50 μm, an average exit width of b = 0.4 mm was obtained. Also in this case it could be observed that with a temperature difference of 80 °C to -30 °C no glass substrate 1 broke or showed damage. It could be shown that shortly after welding these crystals 1 with the welded connecting element 3 were stable against a sudden drop in temperature.

Table 1

Table 2

Table 3

Comparative example The comparative example was carried out in the same way as the example. The difference was in the shape of the connecting element. This was connected according to the prior art to the electrically conductive structure via a rectangular contact surface. The shape of the contact surface did not adapt to the heat distribution profile. No separator was provided on the contact surface. The welding points 15 and 15' were not arranged on contact projections. The dimensions and components of the electrical connection element 3, the metal layer on the contact surface of the connection element 3 and the welding material 4 are found in Table 4. The connection element 3 was electrically welded to the structure 2 conductive according to conventional methods using the welding material 4. With an exit of the welding material 4 from the intermediate space between the electrical connection element 3 and the electrically conductive structure 2, which exceeded a layer thickness t of 50 pm, an average exit width of b = 2 mm was obtained. 3mm

With a sudden temperature difference from 80 °C to -30 °C, it was observed that the glass substrates 1 suffered significant damage shortly after welding.

Table 4

It was shown that the glasses according to the invention with glass substrates 1 and electrical connection elements 3 according to the invention had better stability against sudden temperature differences.

This result was unexpected and surprising to the person skilled in the art.

List of reference signs

(1) Crystal

(2) Electrically conductive structure

(3) Electrical connection element

(4) Welding material

(5) Wetting layer

(6) Compensation member

<(>7<)>Electrical connection element 3 leg region

(7') Leg region of electrical connection element 3

(8) Contact surface of connecting element 3

(8') Contact surface of connection element 3

(8'') Contact surface of connection element 3

(9) Bridge between the 7th and 7th leg regions

(10) Bridge segment 9

(11) Bridge segment 9

(12) Bridge segment 9

(13) Surface of leg region 7 oriented away from substrate 1

(13) Surface of leg region 7 oriented away from substrate 1

(14) Contact highlight

(15) Welding point

(15') Spot Weld

(16) Connection of contact surface 8 and the bottom of bridge 9 (16') Connection of contact surface 8' and bottom of bridge 9 (17) Subregion of bridge 9

(17') Bridge 9 subregion

(18) Bridge 9 subregion

(18') Bridge 9 subregion

(19) Separator

(20) Edge region of connection element 3

(21) Extension element

(22) Bridge segment 9

(23) Bridge segment 9

a Central angle of a circular segment of a contact surface 8' b Maximum outlet width of the welding material

t limiting thickness of the welding material

A-A' Section line

B-B' Section line

C-C' Section line

D-D' Section line

E-E' Section line

F-F' Section line 14

Claims (12)

1. Crystal, which includes: -a substrate (1), -an electrically conductive structure (2) in a region of the substrate (1), -a layer of a lead-free solder material (4) on an electrically conductive region of the structure (2), -at least one electrical connection element (3), containing a chromium-containing steel with a chromium proportion greater than or equal to 10.5% by weight, -at least two welding points (15, 15') of the connection element (3) on the welding material (4), where -the welding points (15, 15') form at least one contact surface (8) between the connection element (3) and the electrically conductive structure (2), and -the shape of the contact surface (8) has at least one oval, ellipse or circle segment with a central angle a of at least 90°. 2. Glass according to claim 1, wherein -the welding points (15,15') form two contact surfaces (8',8"), separated from each other, between the connection element (3) and the electrically conductive structure (2), -the two contact surfaces (8', 8") are connected to each other through the surface of a bridge (9) facing the substrate (1), and -the shape of each of the two contact surfaces (8', 8") has at least one oval, ellipse or circle segment with a central angle a of at least 90°. 3. Glass according to claim 1 or 2, wherein the contact surface (8) or the contact surfaces (8', 8") are configured in the shape of a rectangle with two semicircles arranged on opposite sides. 4. Glass according to claim 2, wherein each contact surface (8', 8") is formed in the form of a circle or a circular segment with a central angle a of at least 180°, preferably at least 220° . 5. Glass according to one of claims 1 to 4, wherein the substrate (1) contains glass, preferably flat glass, float glass, quartz glass, borosilicate glass, soda lime glass or polymers, preferably polyethylene, polypropylene, polycarbonate, polymethacrylate methyl and/or mixtures thereof. 6. Glass according to one of claims 1 to 5, wherein spacers (19) are arranged on the contact surface (8) or on the contact surfaces (8', 8''). 7. Glass according to one of claims 1 to 6, wherein each of the two welding points (15, 15') is arranged on a contact projection (14). 8. Glass according to one of claims 1 to 7, wherein the soldering material (4) contains tin and bismuth, indium, zinc, copper, silver or their compositions. 9. Glass according to claim 8, wherein the proportion of tin in the solder composition (4) is from 3% by weight to 99.5% by weight and the proportion of bismuth, indium, zinc, copper, silver or compositions of these is from 0.5% by weight to 97% by weight. 10. Crystal according to one of claims 1 to 9, wherein the connection element (3) is coated with nickel, tin, copper and/or silver, preferably with between 0.1 pm and 0.3 pm of nickel and/or or between 3 pm and 20 pm silver. 11. Method for the production of a crystal according to one of claims 1 to 10, wherein a) lead-free solder material (4) is applied on the contact surface (8) or on the contact surfaces (8', 8") of the connection element (3) as a platelet with a thickness, volume and shape fixed layer, b) an electrically conductive structure (2) is applied to a region of a substrate (1), c) the connection element (3) with the welding material (4) is arranged on the electrically conductive structure (2), d) energy is introduced into the welding points (15,15'), and e) the connection element (3) is welded to the electrically conductive structure (2). 12. Use of a glass according to one of claims 1 to 10, in vehicles with electrically conductive structures, preferably with heating conductors and/or antenna conductors.